Christopher Duarte swam in darkness for 60 to 90 minutes in 50-degree water to reach shore after the small pleasure boat carrying his family capsized in or near Mount Hope Bay, the Coast Guard said.

At least three of the six people aboard the boat died; the search for a fourth victim, the boy's aunt, was called off late Saturday afternoon.

Duarte told Rose and her husband, Dave, that last time he saw his mother, she was clinging to a fender on the boat, without a life jacket.

Duarte's mother, Edwina, 34, was found alive, but died on the way to the hospital, Coast Guard Petty Officer Andrew Shinn said. Duarte's father, Allen, 35, was rescued and was in critical condition in a hospital.

"This is a family excursion that went awry, and it's a tragedy," Tiverton police chief Thomas Blakey said.

Officials said a change in the weather might have contributed to the accident. Others said there may have been too many people on the 17-foot speedboat.

The boaters, all from Fall River, Mass., had gone out during the day Friday, and had traveled to a relative's waterfront home in Swansea, Mass. The group left Swansea after dark and was heading to a dock in Fall River when the boat capsized, Blakey said.

Skies were clear and temperatures were in the upper 50s to low 60s, but the wind had been picking up throughout the evening. By midnight, it was blowing from the north at 21 mph, with gusts up to 30 mph.

Authorities were investigating precisely where and when the boat capsized. Blakey said it capsized between Fall River and Tiverton, near the point where Mount Hope Bay meets the Sakonnet River, which extends to the south. Mount Hope Bay is a lobe of Narragansett Bay, with shoreline in Massachusetts and Rhode Island.

The Coast Guard called off its active search for the boy's aunt, 24-year-old Kelleigh Ouellette, late Saturday afternoon, Petty Officer Michael Caianiello said. The search was suspended when the Coast Guard determined weather and water conditions made it unlikely that the woman had survived, Caianiello said.

The boy's father was found about 20 minutes after Dave Rose called police. Allen Duarte was suffering from hypothermia and was reported in critical condition at a hospital Saturday.

"The quick response probably saved this guy," Blakey said.

The Roses said they covered Christopher Duarte with blankets. Over and over, they said, he described how he kept himself alive. He remembered a story his grandfather, a shellfisherman, told about his own boat capsizing.

"He said he kept thinking about what his grandfather told him, 'Don't give up. Keep surviving,"' Dave Rose said. "I would say it's nothing short of a miracle he was able to do that."

Some questioned why the family would be on the water in rough conditions, and said the boat may have been overcrowded.

"People don't heed weather warnings," said Don Dettlinger, an assistant harbor master for Tiverton. "It's risky. Why those people were out there last night is beyond my belief. I wouldn't be out if I were on my boat."